1. Field of the Invention
The present invention relates to a process of combining rubber elastomers or polymers to form modified asphalt compositions that are further cross linked or vulcanized with either phenolic or phenol-formaldehyde two-step resins either alone or in combination with each other and/or combinations with elemental sulfur, cross-linking or covulcanization catalysts or agents and (optionally) process oils to produce a product of enhanced performance suitable for commercial, construction and other industrial applications where asphalts or bitumens are to be used.
2. Description of the Prior Art
Polymer modified asphalt or bitumen have been known in the art for many years. The application of such materials has found utility in many fields or areas of the construction industry. These materials have also found utility in many industrial applications. In general these products have met with varying degrees of success in their respective fields of application. The degree of success of each product is related to its ease of process and to the final properties of that same process.
As a result of these previous works, polymer modified asphalts or bitumen offer the skilled technologist many potential process techniques. These techniques may involve the use of a polymer; polymer and oils in various combinations; polymers, oils and cross-linking agents and/or accelerators in combination; and other such similar or like processes in combination with the asphalt or bitumen to produce modified asphalts or bitumen. Among the processes currently available to those skilled in the art that cross link or vulcanize the polymer or rubber to or with the asphalt or bitumen, sulfur is the most widely described. Another process that is available to the skilled artisan is cross-linking or vulcanization by use of urethane chemistry. Although there are other processes described in prior art for vulcanization of polymers in asphalt or bitumen, these two process techniques still remain the most widely used in the industry to date.
As is taught by the previously disclosed art, polymer modification will further enhance asphaltic or bitumen materials and yield a more useful product for many construction or industrial applications. Previous art also discloses or teaches the skilled artisan that cross-linking or vulcanization processes may enhance the rubber or elastomeric polymer asphalt combination beyond that of simple polymer or polymer and oil processing alone.
The prior patents disclose processes for the use of various polymeric materials in asphalt or bitumen to enhance the performance of the resulting product over that of the original asphalt or bitumen. Many of the above patents disclose processes for the cross-linking (in the patents disclosing urethane or other types of cross-linking chemistry) or vulcanization (in the patents disclosing the use of elemental sulfur) many types of rubber or elastomers in or with the asphalt or bitumen.
Of all the prior patents, only one disclosed a process for using an aldehyde, U.S. Pat. No. 3,275,585 issued on Sep. 27, 1966 to L. A. H. Baum, P. F. Bruins and L. Henschel and assigned to Mobile Oil Corporation. In this disclosure the aldehyde is the main source of polymeric material and does not teach or disclose the use of any type of rubber or other elastomeric materials. The use level of the aldehyde is from 1 to 25% and preferably 5 to 15% based upon the weight of the asphalt present. The strong mineral acid catalyst used in the process may be present from 0.1 to 5.0% and preferably 0.1 to 2.0% based upon the weight of the asphalt.
Of all the prior patents, only one disclosed a process for using phenol, U.S. Pat. No. 3,253,521 issued on May 31, 1966 to H. A. Endres and assigned to The Goodyear Tire & Rubber Company. In this disclosure, the phenol is taught to be an antioxidant. It is known in the art that the chemical structure of phenols as antioxidants are not related to or the same as the chemical structure of phenols as cross-linking agents. Specifically, the Endres patent teaches the use of alkylated phenolic structures among others as antioxidants.
All of the prior art patents disclose technology related to methods, compositions or uses of polymer modified asphalts for use in industrial, construction, specialty or other applications. There were no patents or portions there of disclosing either methods, compositions or uses for or of phenolic based cross-linking or vulcanizing resins or reasonable facsimiles thereof in polymer modified asphalts for use in industrial, construction, specialty or other applications.
Many of these previous teachings illustrate enhanced properties such as improved viscosity; better compatibility between the polymer and asphalt or bitumen; higher ball and ring softening points; better heated storage stability; and many other enhancements or improvements to the asphalt or bitumen beyond that of the original material. While the teachings and practice of such processes have met with commercial success in their respective business segments, many of those skilled in the art find that certain limitations in combining rubber polymers, oils and asphalts or bitumen do still exist.
From the previous teachings of the processes disclosed in the current state of the art, it follows that improvements in the art of the vulcanization process which utilize styrene, butadiene and isoprene either alone or in combination and oils and asphalt or bitumen would be of benefit to those skilled in the knowledge of such processes and their products. Therefore, previous to the disclosure of the teachings of the process of this technology using either phenolic or phenol-formaldehyde two-step resins either alone or in combination with each other and/or combinations with elemental sulfur, cross-linking or covulcanization catalysts or agents and (optionally) process oils to produce a product of enhanced performance suitable for commercial, construction and other industrial applications where asphalts or bitumens are to be used were limited. Previous to this disclosure the skilled artisan could not utilize the advantages disclosed here in and attain the properties of the products of said process.